cryptography, zeroisation (also spelled zeroization) is the practice of erasing sensitive parameters (especially keys) from a cryptographic module to prevent their disclosure if the equipment is captured. When encryptionwas performed by mechanical devices, this would often mean changing all the machine's settings to some fixed, meaningless value, such as zero. On machines with letter settings rather than numerals, the letter 'O' was often used instead. Some machines had a button or lever for performing this process in a single step. Zeroisation would typically be performed at the end of an encryption session to prevent accidental disclosure of the keys, or immediately when there was a risk of capture by an adversary.
softwarebased cryptographic modules, zeroisation is made considerably more complex by issues such as virtual memoryand compileroptimisations. Also, zeroisation may need to be applied not only to the key, but also to a plaintextand some intermediate values. A cryptographic software developer must have an intimate understanding of memory management in a machine, and be prepared to zeroise data whenever a sensitive location might move outside the security boundary. Typically this will involve overwriting the data with zeroes, but in the case of some types of non-volatile storagethe process is much more complex; see " data remanence".
As well as zeroising data due to memory management, software designers consider performing zeroisation:
* When an application changes mode (e.g. to a test mode) or user;
* When a
computer processchanges privileges;
* On termination (including abnormal termination);
* On any error condition which may indicate instability or tampering;
* Upon user request;
* Immediately, the last time the parameter is required; and
* Possibly if a parameter has not been required for some time.Informally, software developers may also use zeroise to mean any overwriting of sensitive data, not necessarily of a cryptographic nature.
In tamper resistant hardware, automatic zeroisation may be initiated when tampering is detected. Such hardware may be rated for cold zeroisation, the ability to zeroise itself without its normal
Standards for zeroisation are specified in ANSI X9.17 and
Wikimedia Foundation. 2010.
Look at other dictionaries:
Zeroisation — An ISO term. A method of erasing or overwriting electronically stored data … International financial encyclopaedia
Tamper resistance — is resistance to by either the normal users of a product, package, or system or others with physical access to it. There are many reasons for employing tamper resistance.Tamper resistance ranges from simple features like screws with special heads … Wikipedia
Zero (disambiguation) — Zero is the name for both the digit 0 and the number 0.Zero may also refer to:Mathematics*Zero (complex analysis), in mathematics, a root of a holomorphic function *Zero element, in mathematics, a generalization of the number zero to other… … Wikipedia
List of cryptographic key types — This glossary lists types of keys as the term is used in cryptography, as opposed to door locks. Terms that are primarily used by the U.S. National Security Agency are marked (NSA) . For classification of keys according to their usage see… … Wikipedia
Data remanence — is the residual representation of data that remains even after attempts have been made to remove or erase the data. This residue may result from data being left intact by a nominal file deletion operation, by reformatting of storage media that… … Wikipedia
Glossary of cryptographic key types — This glossary lists types of keys as the term is used in cryptography, as opposed to door locks. Terms that are primarily used by the U.S. National Security Agency are marked (NSA). For classification of keys according to their usage see… … Wikipedia